Pharmaceutical-grade ferric organic compounds, uses thereof and method of making same

ABSTRACT

The present invention discloses pharmaceutical-grade ferric organic compounds, including ferric citrate, which are soluble over a wider range of pH, and which have a large active surface area. A manufacturing and quality control process for making a pharmaceutical-grade ferric citrate that consistently complies with the established Manufacture Release Specification is also disclosed. The pharmaceutical-grade ferric organic compounds are suitable for treating disorders characterized by elevated serum phosphate levels.

This application is a Continuation of U.S. Ser. No. 12/064,058, filedFeb. 18, 2008, which is a National Stage of International ApplicationNo. PCT/US2006/032385, filed Aug. 18, 2006, which claims benefit of U.S.Ser. No. 60/709,511, filed Aug. 19, 2005, and U.S. Ser. No. 11/206,981,filed Aug. 18, 2005, which is a Continuation-In-Part of Int'l App'l No.PCT/US2004/004646, filed Feb. 18, 2004, which claims benefit of U.S.Ser. No. 60/462,684, filed Apr. 15, 2003, and U.S. Ser. No. 60/447,690,filed Feb. 19, 2003, and the entire contents and disclosures of thepreceding applications are incorporated herein by reference into thisapplication.

Throughout this application, various publications are referenced.Disclosures of these publications in their entireties are herebyincorporated by reference into this application to more fully describethe state of the art to which this invention pertains.

TECHNICAL FIELD

This invention relates to the preparation and use ofpharmaceutical-grade ferric organic compounds, such as ferric citrate.Uses of the pharmaceutical-grade ferric citrate described herein,include, but are not limited to methods of treating various disorders inhumans and non-human subjects or patients.

BACKGROUND OF THE INVENTION Uses of Iron Compounds

Ferric iron containing compounds are useful in the treatment of a numberof disorders, including, but not limited to, hyperphosphatemia andmetabolic acidosis. See Hsu et al., “New Phosphate Binding Agents:Ferric Compounds”, J Am Soc Nephrol, Vol. 10, Pages 1274-1280, 1999.Previous studies and inventions have reported the use of ferriccompounds in binding with dietary phosphates, and such ferric compoundsare potentially useful for the treatment of hyperphosphatemia in renalfailure patients (U.S. Pat. No. 5,753,706, 1998; U.S. Pat. No.6,903,235, 2005; CN 1315174, 2001; Yang W. C., et al., Nephrol. Dial.Transplant 17:265:270 (2002)). Elevated amounts of phosphate in theblood can be removed by administering compounds such as ferric citrate.Once in solution, the ferric iron binds phosphate, and the ferricphosphate compounds precipitate in the gastrointestinal tract, resultingin effective removal of dietary phosphate from the body. It is alsobelieved that the absorbed citrate from ferric citrate is converted tobicarbonate which corrects metabolic acidosis, a condition common inrenal failure patients.

Int'l App. No. PCT/US2004/004646, filed Feb. 18, 2004, published underInt'l Publication No. WO2004/074444 on Sep. 2, 2004, discloses a methodof preparing ferric organic compounds, including ferric citrate thatremains soluble over a wider range of pH than previously describedpreparations, and which have a large active surface area. However,commercially scalable manufacturing processes with qualitycontrol/analysis measures to ensure and/or to verify the compliance ofthe pharmaceutical-grade ferric citrate or ferric organic compounds withestablished standards or specifications were not previously disclosed.

Accordingly, there exists a need for a scalable process for synthesizingpharmaceutical-grade ferric organic compounds or ferric citrate forhuman use. The process needs to consistently produce ferric organiccompounds or ferric citrate of the required pharmaceutical grade.

This invention further discloses dosage for ferric citrate for treatingof a human or non-human subject or patient. in need of the compound.Different routes of administration are explored.

SUMMARY OF THE INVENTION

In accordance with these and other objects of the invention, a briefsummary of the present invention is presented. Some simplifications andomission may be made in the following summary, which is intended tohighlight and introduce some aspects of the present invention, but notto limit its scope. Detailed descriptions of a preferred exemplaryembodiment adequate to allow those of ordinary skill in the art to makeand use the invention concepts will follow in later sections.

An embodiment of the invention provides a manufacturing and qualitycontrol process/analysis for making a pharmaceutical-grade ferriccitrate that consistently complies with the established ManufactureRelease Specification. The process of the present invention can beadapted to produce multi-kilogram batches of pharmaceutical-grade ferriccitrate, and can be readily scaled up to provide additionalmanufacturing capacity for ferric citrate.

An illustrative embodiment of the manufacturing method may beexemplified by the following non-limiting sequence of steps forpreparing pharmaceutical-grade ferric citrate comprising the steps of:(a) dissolving an appropriate amount of Ferric chloride hexahydrate inwater to form a Ferric chloride hexahydrate solution; (b) dissolving anappropriate amount of NaOH in water to form a NaOH solution; (c) mixingthe Ferric chloride hexahydrate solution and NaOH solution to form asolution with Fe(OH)₃ precipitate; (d) maintaining the pH of thesolution with Fe(OH)₃ precipitate above 7.0; (e) isolating the Fe(OH)₃precipitate; (f) washing the Fe(OH)₃ precipitate three times with water;(g) suspending the Fe(OH)₃ precipitate in water; (h) adding citric acidto the Fe(OH)₃ precipitate to form a ferric-organic acid solution; (i)stirring and heating the ferric-organic acid solution at 90-100° C. for30 to 120 minutes; (j) removing solids in the ferric-organic acidsolution by adding citric acid; (k) allowing the ferric-organic acidsolution to cool to below 30° C.; (l) maintaining the pH of theferric-organic acid solution to between 0.8-1.5; (m) filtering theferric-organic acid solution to obtain a liquid filtrate; (n) mixingacetone and liquid filtrate to form ferric citrate; (o) isolating ferriccitrate; (p) washing ferric citrate with acetone three times; and (q)drying the ferric citrate.

A further embodiment provides a large-scale production scheme forpharmaceutical-grade ferric citrate comprising the steps of: (a) mixingan appropriate amount of NaOH and Ferric chloride hexahydrate in asuitable reactor to form a ferric hydroxide slurry with ferric hydroxideprecipitate; (b) maintaining the pH of the ferric hydroxide slurry toabove 7.0; (c) isolating the ferric hydroxide precipitate from theferric hydroxide slurry using pressure filtration; (d) washing theferric hydroxide precipitate three times; (e) maintaining the % Cl inthe ferric hydroxide precipitate to below 5%; (f) isolating the washedferric hydroxide precipitate using pressure filtration; (g) mixingcitric acid with washed ferric hydroxide precipitate to form a ferricorganic acid solution; (h) stirring and maintaining the temperature ofthe ferric organic acid solution at 80±5° C. for 2 hours; (i) allowingthe ferric organic acid solution to cool to 60° C.; (j) maintaining thepH of the ferric organic acid solution to between 0.8 to 1.5 and theamount of Fe in the ferric organic acid solution to ≧85% of Fe added instep (a); (k) filtering the ferric organic acid solution using pressurefiltration to obtain a liquid filtrate; (l) mixing the liquid filtratewith acetone to obtain ferric citrate; (m) isolating ferric citrateusing pressure filtration; (n) washing the ferric citrate with acetone;(o) isolating the washed ferric citrate using pressure filtration; (p)drying the washed ferric citrate in fluidized bed dryer; and (q)maintaining the organic volatile impurities to ≦1000 ppm acetone.

A further embodiment encompasses various intermediate compositions thatmay be useful in the preparation of the pharmaceutical-grade ferriccitrate. The intermediate compositions encompassed herein includesolids, liquids or multiphase mixtures. A liquid intermediatecomposition comprising the pharmaceutical-grade ferric citrate may be anaqueous composition or an organic solvent-based composition. Amultiphase composition may encompass both aqueous and organic phases.

An additional embodiment encompasses the methods of storing, packagingand using the various intermediate compositions disclosed herein.

An additional embodiment provides pharmaceutically useful compositionscomprising the pharmaceutical-grade ferric citrate. The pharmaceuticallyuseful composition further comprises any pharmaceutically acceptablecarrier, adjuvant, filler or delivery vehicle suitable for administeringto a subject or human patient, an effective amount of thepharmaceutical-grade ferric citrate.

Further embodiments of the pharmaceutical compositions include, but arenot limited to solids, liquids, or semi-solid forms, such as gels,syrups, chewables or pastes. Within the scope of the methods of usingthe pharmaceutically useful compositions disclosed herein are effectivedoses of the pharmaceutical compositions, in addition to the timing andmodes of administering the pharmaceutical compositions.

A non-limiting example of a method for using the pharmaceuticalcompositions encompasses treating disorders resulting from elevatedblood levels of phosphates, i.e., hyperphosphateimia, in a subject or ahuman patient. Such disorders are exemplified by, but not limited to,renal failure or the progression of renal failure, mineralization ofsoft tissues, hyperparathyroidism as well as other complications.

An embodiment encompassed by the invention includes a pharmaceuticalcomposition comprising:

-   (a) an amount of a pharmaceutical-grade ferric organic compound    effective to achieve a decrease in the serum phosphate level of a    subject or patient;-   (b) a pharmaceutically suitable carrier; and-   wherein the ferric organic compound complies with at least one of    the limits in the manufacture release specification in Table A.

The pharmaceutical composition described herein may be prepared by amethod shown in FIG. 1, 2, 3 or 4. Further to these embodiments arecompositions prepared with materials satisfying at least one limitdisclosed in each of the release specifications of either of therelevant Tables B to F.

An additional embodiment encompasses compositions ofpharmaceutical-grade ferric citrate, prepared according to methodscomprising the steps of:

-   -   (a) dissolving an appropriate amount of ferric chloride        hexahydrate in water to form a ferric chloride hexahydrate        solution;    -   (b) dissolving an appropriate amount of NaOH in water to form a        NaOH solution;    -   (c) mixing the ferric chloride hexahydrate solution and NaOH        solution to form a solution with Fe(OH)3 precipitate;    -   (d) maintaining the pH of the solution with Fe(OH)₃ precipitate        above 7.0;    -   (e) isolating the Fe(OH)₃ precipitate;    -   (f) washing the Fe(OH)₃ precipitate three times with water;    -   (g) suspending the Fe(OH)₃ precipitate in water;    -   (h) adding citric acid to the Fe(OH)₃ precipitate to form a        ferric-organic acid solution;    -   (i) stirring and heating the ferric-organic acid solution at        90-100° C. for 30 to 120 minutes;    -   (j) removing solids in the ferric-organic acid solution by        adding citric acid;    -   (k) allowing the ferric-organic acid solution to cool to below        30° C.;    -   (l) maintaining the pH of the ferric-organic acid solution to        between 0.8-1.5;    -   (m) filtering the ferric-organic acid solution to obtain a        liquid filtrate;    -   (n) mixing acetone and liquid filtrate to form ferric citrate;    -   (o) isolating ferric citrate;    -   (p) washing ferric citrate with acetone three times;    -   (q) drying the ferric citrate; and    -   (r) performing quality control tests as shown in FIG. 1, 2 or 3.

It is advantageous to scale-up the method of preparation. Thus, anindustrial-scale method is embodied by a method for large-scaleproduction of pharmaceutical-grade ferric citrate comprising the stepsof:

-   -   (a) mixing an appropriate amount of NaOH and Ferric chloride        hexahydrate in a suitable reactor to form a ferric hydroxide        slurry with ferric hydroxide precipitate;    -   (b) maintaining the pH of the ferric hydroxide slurry to above        7.0;    -   (c) isolating the ferric hydroxide precipitate from the ferric        hydroxide slurry using pressure filtration;    -   (d) washing the ferric hydroxide precipitate three times;    -   (e) maintaining the % Cl in the ferric hydroxide precipitate to        below 5%;    -   (f) isolating the washed ferric hydroxide precipitate using        pressure filtration;    -   (g) mixing citric acid with washed ferric hydroxide precipitate        to form a ferric organic acid solution;    -   (h) stirring and maintaining the temperature of the ferric        organic acid solution at 80±5° C. for 2 hours;    -   (i) allowing the ferric organic acid solution to cool to 60° C.;    -   (j) maintaining the pH of the ferric organic acid solution to        between 0.8 to 1.5 and the amount of Fe in the ferric organic        acid solution to ≧85% of Fe added in step (a);    -   (k) filtering the ferric organic acid solution using pressure        filtration to obtain a liquid filtrate;    -   (l) mixing the liquid filtrate with acetone to obtain ferric        citrate;    -   (m) isolating ferric citrate using pressure filtration;    -   (n) washing the ferric citrate with acetone;    -   (o) isolating the washed ferric citrate using pressure        filtration;    -   (p) drying the washed ferric citrate in fluidized bed dryer; and    -   (q) maintaining the organic volatile impurities to 1000 ppm        acetone;    -   and wherein the ferric citrate complies with at least one of the        limits in the manufacture release specification in Table A.

The compositions encompassing pharmaceutical grade ferric citrate aresuitable for treating hyperphosphatemia, or other disorderscharacterized by high serum phosphate levels. Therefore, the inventionencompasses treating subjects or patients with various renal diseases;e.g., End Stage Renal Diseases (ESRD), Chronic Kidney Disease (CKD) orother relate kidney diseases, or subjects and patients who are ondialysis but not limited to hemodialysis.

In another embodiment, the compositions encompassing pharmaceuticalgrade ferric citrate may used to treat subjects or patients withmetabolic acidosis. Other disorders that may be ameliorated by theconversion of citrate to bicarbonate are also encompassed by theinvention described.

An embodiment of a method for using the pharmaceutical compositionencompasses treating a human or non-human subject or patient withchronic kidney disease. There are generally five clinical stages ofchronic kidney disease, numbered 1 to 5, wherein stage 1 is the leastsevere and stage 5 the most severe. In the early stages, e.g., stagesand 2, dialysis is not required. As chronic kidney disease progresses tostage 5, a patient may require dialysis treatment three times per week.It should be noted that elevated phosphate levels are observed at allstages of chronic kidney disease. Therefore, an embodiment of theinvention is a method of treating a subject or person with early ormid-stage chronic kidney disease, with a composition comprisingpharmaceutical-grade ferric citrate in order to achieve a lower serumphosphate level.

It is a further embodiment of the invention to provide a method oftreating a human or non-human subject or patient with late-stage chronickidney disease who undergo hemodialysis, by administering a compositioncomprising pharmaceutical-grade ferric citrate. It is known thathemodialysis is not sufficiently effective in reducing serum phosphatelevel. The treatment of a subject or person with late stage kidneydisease is applicable whether or not the subject or person is currentlyundergoing hemodialysis treatment.

An additional embodiment of the invention is a method of treating asubject or person with chronic kidney disease and undergoing peritonealdialysis with the pharmaceutical-grade ferric citrate-containingcompositions described. It is known that peritoneal dialysis is notsufficiently effective in reducing serum phosphate levels.

An additional embodiment is a method for using the pharmaceuticalcomposition to inhibit or even reverse soft tissue mineralization,specifically calcification. Hyperphosphatemia may lead to increasedcalcium phosphate deposition in hard and soft tissues by increasing thelikelihood of binding with free calcium to form insoluble calciumphosphate. Therefore, an effective dose of a composition comprisingpharmaceutical-grade ferric citrate may decrease serum phosphate levelsand result in a corresponding decrease in calcium phosphate deposition.

It is noteworthy that whereas ferric ion forms insoluble precipitateswith phosphate-containing compounds in the lumen of thegastroinstestinal tract, the citrate component is absorbed and functionsas a calcium chelator. Because chelated calcium is not available forcalcium phosphate formation, administering pharmaceutical-grade ferriccitrate decreases may lead to reductions in both serum calcium andphosphate. This may also be expressed as leading to a decrease in theserum calcium-phosphate product. Reducing serum calcium and phosphatewould be expected to reduce calcium phosphate deposition. The end resultis reversing, i.e., solubilizing or dissolving, the deposited calciumphosphate.

The decalcifying of a calcified soft tissue, e.g., the sclera of theeye, may be achieved by administering pharmaceutical-grade ferriccitrate. It is known among persons of ordinary skill in the relevantmedical arts that patients with kidney disease receiving doses of ferriccitrate have shown reversal of calcium deposits on the eye. Therefore,an embodiment of the invention is directed to the decalcification ofsoft tissue such as the eye.

Kidney stones comprise calcium salts of oxalic acid or phosphates andare formed by mechanisms similar to those described above. Thus,pharmaceutical-grade ferric citrate, in another embodiment of theinvention provides a method of treating kidney stones, i.e., renalcalculi, by promoting their dissolution.

The compositions encompassing pharmaceutical grade ferric citrate mayoperate according to more than one mechanism. A plausible non-limitingmechanism of action may result from the ferric ion binding phosphate inthe GI tract, thus forming an insoluble ferric phosphate precipitate.This, in turn, may result in decrease the uptake of phosphate andphosphate-containing compounds from the GI tract.

In view of such a mechanism, the administering of compositionsencompassing pharmaceutical grade ferric citrate via an oral route isencompassed by the inventive methods described.

This invention provides a method of reversing, preventing or stabilizingsoft tissue calcification of a subject, comprising administering to saidsubject and effective amount of a ferric citrate compound.

This invention further provides a method of reversing, preventing orstabilizing soft tissue calcification of a subject, comprisingadministering to said subject and effective amount of a ferric citratecompound, wherein the ferric citrate compound is prepared according to amethod as shown in FIGS. 1-4.

This invention provides a method of reversing, preventing or stabilizingsoft tissue calcification of a subject, comprising administering to saidsubject and effective amount of a ferric citrate compound, wherein theferric citrate compound is prepared according a method comprising thesteps of:

An embodiment of the invention encompasses tolerable doses of up to 15grams per day for ferric citrate capsules and 30 grams per day forferric citrate tablets.

The compositions encompassing pharmaceutical grade ferric citrate may beadministered for varying periods of time. In some embodiments, thetolerability of the compositions encompassing pharmaceutical gradeferric citrate allows for long term administration when necessary.

DETAILED DESCRIPTION OF THE FIGURES

In drawings which illustrate specific embodiments of the invention, butwhich should not be construed as restricting the spirit or scope of theinvention in any way:

FIG. 1 is a schematic diagram outlining the general method for synthesisof pharmaceutical-grade ferric citrate including in-process qualitycontrol measures to ensure the final ferric citrate product complieswith the established Manufacture Release Specification as shown in TableA.

FIG. 2 is a schematic diagram outlining a method of makingpharmaceutical-grade ferric citrate according to the invention.

FIG. 3 shows an overview of scalable pharmaceutical-grade ferric citratemanufacturing and quality control process according to the invention.

FIG. 4 is a schematic diagram of scalable pharmaceutical-grade ferriccitrate manufacturing and quality control process according to theinvention.

FIG. 5 shows the representative proton NMR spectrum for apharmaceutical-grade ferric citrate according to the invention.

FIG. 6 shows the representative FTIR spectrum for pharmaceutical-gradeferric citrate according to the invention.

FIG. 7 is a comparison of intrinsic dissolution rates at pH 1.0 and 8.0for pharmaceutical grade and chemical grade ferric citrate.

FIG. 8 is a schematic diagram outlining the general method for synthesisof pharmaceutical-grade ferric organic compound including in-processquality control measures to ensure the final ferric organic compoundcomplies with established Manufacture Release Specification.

FIG. 9 is a summary of clinical results for pharmaceutical-grade ferriccitrate

FIG. 10 is a summary of the efficacy data for pharmaceutical-gradeferric citrate

FIG. 11 is a summary of the safety data from a clinical study

FIG. 12 is a comparison of the safety profiles of chemical grade andpharmaceutical grade ferric citrates

FIG. 13 is a comparison of the efficacy profiles of chemical grade andpharmaceutical grade ferric citrates

FIG. 14 shows a bar graph of the relationship between the rate ofdialysis patient mortality and hyperphosphatemia

DETAILED DESCRIPTION OF THE INVENTION

In drawings which illustrate specific embodiments of the invention, butwhich should not be construed as restricting the spirit or described indetail to avoid unnecessarily obscuring the invention. Accordingly, thespecification and drawings are to be regarded in an illustrative, ratherthan a restrictive, sense.

Throughout this application, references are made to the United StatsPharmacopeia (USP), and the latest edition of the USP, USP 28, is herebyincorporated by reference into this application in its entirety.

This invention provides a method of preparing pharmaceutical-gradeferric citrate, comprising the steps of: (a) dissolving an appropriateamount of Ferric chloride hexahydrate in water to form a Ferric chloridehexahydrate solution; (b) dissolving an appropriate amount of NaOH inwater to form a NaOH solution; (c) mixing the Ferric chloridehexahydrate solution and NaOH solution to form a solution with Fe(OH)₃precipitate; (d) maintaining the pH of the solution with Fe(OH)₃precipitate above 7.0; (e) isolating the Fe(OH)₃ precipitate; (f)washing the Fe(OH)₃ precipitate three times with water; (g) suspendingthe Fe(OH)₃ precipitate in water; (h) adding citric acid to the Fe(OH)₃precipitate to form a ferric-organic acid solution; (i) stirring andheating the ferric-organic acid solution at 90-100° C. for 30 to 120minutes; (j) removing solids in the ferric-organic acid solution byadding citric acid; (k) allowing the ferric-organic acid solution tocool to below 30° C.; (l) maintaining the pH of the ferric-organic acidsolution to between 0.8-1.5; (m) filtering the ferric-organic acidsolution to obtain a liquid filtrate; (n) mixing acetone and liquidfiltrate to form ferric citrate; (o) isolating ferric citrate; (p)washing ferric citrate with acetone three times; and (q) drying theferric citrate.

This invention provides a method for scalable or large-scale productionof pharmaceutical-grade ferric citrate comprising the steps of: (a)mixing an appropriate amount of NaOH and Ferric chloride hexahydrate ina suitable reactor to form a ferric hydroxide slurry with ferrichydroxide precipitate; (b) maintaining the pH of the ferric hydroxideslurry to above 7.0; (c) isolating the ferric hydroxide precipitate fromthe ferric hydroxide slurry using pressure filtration; (d) washing theferric hydroxide precipitate three times; (e) maintaining the % Cl inthe ferric hydroxide precipitate to below 5%; (f) isolating the washedferric hydroxide precipitate using pressure filtration; (g) mixingcitric acid with washed ferric hydroxide precipitate to form a ferricorganic acid solution; (h) stirring and maintaining the temperature ofthe ferric organic acid solution at 80±5° C. for 2 hours; (i) allowingthe ferric organic acid solution to cool to 60° C.; (j) maintaining thepH of the ferric organic acid solution to between 0.8 to 1.5 and theamount of Fe in the ferric organic acid solution to ≧85% of Fe added instep (a); (k) filtering the ferric organic acid solution using pressurefiltration to obtain a liquid filtrate; (l) mixing the liquid filtratewith acetone to obtain ferric citrate; (m) isolating ferric citrateusing pressure filtration; (n) washing the ferric citrate with acetone;(o) isolating the washed ferric citrate using pressure filtration; (p)drying the washed ferric citrate in fluidized bed dryer; and (q)maintaining the organic volatile impurities to ≦1000 ppm acetone.

In an embodiment, the ferric chloride hexahydrate complies with therelease specification as shown in Table B; the citric acid complies withthe release specification as shown in Table F; the water complies withthe release specification as shown in Table D; the acetone complies withthe release specification as shown in Table E; and the sodium hydroxidecomplies with the release specification as shown in Table C.

In another embodiment, the ferric citrate is dried using a fluidized beddryer or is dried under vacuum.

In a further embodiment, the process as described above furthercomprises testing the ferric citrate for compliance with the releasespecification as shown in Table A. In a further embodiment, testingcomprises performing at least one test selected from the groupconsisting of: assay content purity of ferric citrate and ferric citratemonohydrate; assay content of citric acid; assay content of detectableferric citrate related substances; assay content of ferric ion;elemental iron impurity test; limit of ferrous iron test; loss on dryingtest; hydrate test (water content by differential scanning calorimetry);hydrate test (water content by karl Fischer Titration); trace or heavymetals test (As, Ca, Cd, Cu, Fe, Hg, Na, Pb, Sr, Zn); limit of oxalicacid test; identification A for ferric salts test; identification B byFTIR test; insoluble substances test; limit of ammonium test; limit ofchloride test; limit of nitrate test; limit of tartrate test; residue onignition test; organic volatile impurities test; and microbial, mold andyeast test.

This invention provides a pharmaceutical-grade ferric citrate preparedaccording to the methods described above.

This invention provides a composition comprising the ferric citrateprepared according to the methods described above for treatinghyperphosphatemia or metabolic acidosis.

This invention provides a composition prepared according to the methodsdescribed above for treating disorders responsive to ferric organiccompound therapy.

This invention provides a pharmaceutical-grade ferric citrate preparedaccording to the methods described above, wherein the ferric citrateproduces the peak as shown in FIG. 6 when subjected to NMR spectroscopyanalysis.

This invention provides a pharmaceutical-grade ferric citrate preparedaccording to the methods described above, wherein the ferric citratepossesses the dissolution rates as shown in FIG. 8.

This invention provides a pharmaceutical-grade ferric citrate preparedaccording to the methods described above, wherein the ferric citrateproduces the spectral data as shown in FIG. 7 when subjected to FourierTransform Infrared Spectrometry (FTIR) spectrum analysis.

This invention provides a composition comprising the ferric citrate asdescribed above for treating hyperphosphatemia or metabolic acidosis.

This invention provides a composition comprising the ferric acid asdescribe above for treating disorders responsive to ferric organiccompound therapy.

This invention provides a pharmaceutical-grade ferric citrate preparedby the process comprising the steps as shown in FIG. 1-4.

The pharmaceutical-grade ferric citrate according to the invention isuseful for treating a subject suffering from hyperphosphatemia,metabolic acidosis or a disorder responsive to ferric organic compoundtherapy. In an embodiment, the subject is a human being.

The invention also provide a use for a composition comprisingpharmaceutical-grade ferric citrate effective for one or more of thefollowing uses,

-   -   (a) treating hyperphosphatemia;    -   (b) decreasing mortality rate in dialysis patients;    -   (c) treating metabolic acidosis;    -   (d) inhibiting calcium phosphate deposition;    -   (e) decreasing serum calcium-phosphate product ([Ca]×[P])    -   (f) decreasing serum calcium levels;    -   (g) reversing calcification of soft tissue; and    -   (h) aiding to dissolve a kidney stone.

The use may further encompass at least partly relying on reducing serumlevels of calcium and phosphate ions.

The uses as stated above may apply to soft tissue such as a blood vesselor an eye.

The uses as stated may be carried out by administering over a long-term.

The invention allows for the above-stated uses to be achieved whereinthe use is accompanied by less gastrointestinal adverse side effectsthan if the composition comprised chemical grade ferric citrate.

In accordance with the above-stated uses, the invention provides for amethod for treating a disorder characterized by a high serum phosphatelevel comprising administering an effective amount of a compositioncomprising pharmaceutical-grade ferric citrate.

The invention also provides for the method wherein an effective amountof pharmaceutical-grade ferric citrate is administered in the form of atablet, a powder, a suspension, an emulsion, a capsule, a lozenge, agranule, a troche, a pill, a liquid, a spirit, or a syrup.

The invention also provides for the method wherein the effective amountof pharmaceutical-grade ferric citrate is from 2 to 100 grams per day,preferably between 4 and 60 grams per day.

In some embodiments, the method may provide a daily effective amount of2, 4, 6, or 8 grams.

In general, hyperphosphatemia is prevalent in patients with chronicrenal failure and in patients on dialysis. There is also evidence thatindicate elevated serum phosphorus, calcium-phosphorus product (Ca×P)and parathyroid hormone (PTH) levels contribute to increased incidenceof vascular, visceral, peripheral vascular and soft tissue calcificationin renal disease patients

Thus, it is an additional novel feature of the claimed invention toprevent or reverse calcification in renal disease patient or in a normalperson. For example, dissolving kidney stones that may accompany renalfailure.

Phosphorous exerts a negative impact on vascular calcification by directparticipation in the Ca×P and indirectly in the pathogenesis andprogression of hyperthyroidism. Serum calcium and phosphorous aremetastable under normal circumstances, which means that theirconcentrations are not sufficient to produce spontaneous precipitation.However, once the calcification process begins, the concentrations aresufficient to support crystal proliferation.

Available evidence confirms a high prevalence of underlying vasculardisease and structural heart disease in patients with severe chronicrenal failure. These structural lesions are then exposed to elevatedserum phosphorus, Ca×P, and PTH(1).

Factors which are considered likely to contribute to elevated serumphosphorus and Ca×P include administration of calcium-containingphosphorus binders. The calcium-containing phosphorus binders, such ascalcium acetate are prescribed to many new hemodialysis (HD) andperitoneal dialysis (PD) patients, thus providing a large source ofexogenous calcium to the GI tract.

Calcification also extends beyond renal disease patients and can includeanyone who is over the age of 40. While the leading cause of death inthe United States is acute myocardial infarction and stroke,hypercholesteromia contribute to only 15% of the deaths in this categoryand 85% is caused by ventricular calcification.

It has been shown that abnormalities in serum phosphorous, Ca×P and PTHlevels can result in vascular, visceral and/or soft tissuecalcification. For example, calcifications of myocardium, coronaryarteries, cornea can lead to the development of a number of clinicallysignificant complications including myocardial ischemia, myocardialinfarction, impaired myocardial function, congestive heart failure,cardiac valve insufficiency and blindness.

Accordingly, there exists a need for methods of managing or reducingserum phosphorous as a means of treating numerous medical disorders. Themethod includes administering a phosphate binder which does notadversely affect serum calcium levels and does not cause toxic sideeffects in the patient.

EXAMPLES

In examples which are intended to illustrate embodiments of theinvention but which are not intended to limit the scope of theinvention:

Example 1 General Method for Synthesis of a Pharmaceutical-Grade FerricCitrate

Referring to FIG. 1, which shows a general method of synthesis of thepharmaceutical-grade ferric citrate according to the invention, the flowchart shows implementation of quality control measures at selectedstages of the synthesis process to ensure the final ferric citrateproduct complies with the Manufacture Release Specification as shown inTable A or any established Manufacture Release Specification forpharmaceutical-grade ferric citrate which have been approved or aresuitable for human use. Other quality control measures or procedures,which are readily apparent to one of ordinary skill in the art, can beused or incorporated into the pharmaceutical-grade synthesis process tomaintain the quality and purity of the final product and to increase theefficiency and yield of the synthesis process. See, for example, QC10and QC11 in FIG. 1.

Examples of quality control measures employed in the synthesis processinclude: (QC4) maintaining pH of the ferric hydroxide slurry above 7.0;(QC5) maintaining the % Cl in ferric hydroxide precipitate below 5%;(QC7) maintaining the pH of the mixture between 0.8-1.5 and the Fe inmixture ≧85% of total Fe added after adding citric acid to ferrichydroxide precipitate; and (QC9) maintaining the level of acetone to≦1000 ppm during the drying stage.

In an embodiment, the raw materials, i.e., ferric chloride, deionizedwater, citric acid, acetone, sodium hydroxide, must pass releasespecifications, such as those provided on Table B-F, before they can beused in the synthesis process. See FIG. 1, QC1-QC3, QC6 and QC8.

Example 1A General Method for Synthesis of a Pharmaceutical-Grade FerricOrganic Compounds

Referring to FIG. 10, which shows a general method of synthesis of thepharmaceutical-grade ferric organic compounds according to theinvention, the flow chart shows implementation of quality controlmeasures at selected stages of the synthesis process to ensure the finalferric citrate product complies with established Manufacture ReleaseSpecification for pharmaceutical-grade ferric organic compounds whichhave been approved or are suitable for human use. Other quality controlmeasures or procedures, which are readily apparent to one of ordinaryskill in the art, can be used or incorporated into thepharmaceutical-grade synthesis process to maintain the quality andpurity of the final product and to increase the efficiency and yield ofthe synthesis process. See, for example, QC10A and QC11A in FIG. 10.

Examples of quality control measures employed in the synthesis processinclude: (QC4A) maintaining pH of the ferric hydroxide slurry above 7.0;(QC5A) maintaining the % Cl in ferric hydroxide precipitate below 5%;(QC7A) maintaining the pH of the mixture between 0.8-1.5 and the Fe inmixture ≧85% of total Fe added after adding organic acid to ferrichydroxide precipitate; and (QC9A) maintaining the level of organicsolvent to ≦1000 ppm during the drying stage.

In an embodiment, the raw materials, i.e., ferric iron salt, deionizedwater, organic acid, organic solvent, alkaline metal hydroxide, mustpass release specifications before they can be used in the synthesisprocess. See FIG. 1, QC1A-QC3A, QC6A and QC8A. The organic acid cancomprise citric acid, acetic acid, isocitric acid, succinic acid,fumaric acid, tartaric acid, or any other suitable organic acid. Theorganic solvent can comprise ethanol, methanol, butanol, acetone,isopropyl alcohol, tetrahydrofuran, or any other suitable organicsolvent.

Example 2 Solubility Profile of Ferric Organic Compounds According tothe Invention

The ferric organic compounds produced according to the methods describedabove are more soluble than commercially available ferric organiccompounds, over a wider range of pH levels. This increase in solubilityof the ferric organic compounds of the present invention is believed tobe a result of the unique significantly large active surface area of theferric organic compounds of the present invention. For example, at pH8.0, the intrinsic dissolution rate of ferric citrate of the presentinvention is 3.08 times greater than the commercially available ferriccitrate. See Table 1.

The intrinsic dissolution rates of commercially available ferric citratewere compared with the ferric citrate of the present invention. Theintrinsic dissolution rate is defined as the dissolution rate of puresubstances under the condition of constant surface area. The dissolutionrate and bioavailability of a drug substance is influence by its solidstate properties: crystallinity, amorphism, polymorphism, hydration,solvation, particle size and particle surface area. The measuredintrinsic dissolution rate is dependent on these solid-state propertiesand is typically determined by exposing a constant surface area of amaterial to an appropriate dissolution medium while maintaining constanttemperature, stirring rate, and pH. The intrinsic dissolution rates arepresented in Table 1.

TABLE 1 Intrinsic dissolution rates of ferric citrate at 37° C. insolutions of pH 8 Intrinsic Mean Rate of Dissolution Intrinsic AcetoneRates Dissolution Addition (mg/ Rates Sample (ml/min) cm2/min)(mg/cm2/min) RFS-12 (sigma/ 10.0 0.83 0.83 commercially available)STM-134 10.0 1.88 3.08 (reference material) PAN031203A 10.0 3.82(experimental batch 1) PAN031203B 10.0 4.00 (experimental batch 2)PAN031203C 9.5 2.68 (experimental batch 3) PAN031203D 40 2.95(experimental batch 4) PAN031203E 4.4 3.13 (experimental batch 5)

For example, the BET active surface area of the ferric citrate of thepresent invention is at least 16 times larger than the commerciallyavailable ferric citrate. See Table 2.

The analysis of active surface area is based on BET theory whichdescribes the phenomenon of mass and energy interaction and phasechanges during gas adsorption onto solid surfaces and in pore spaces. InBET active surface area measurement, the volume of a monolayer of gas isdetermined which allows the surface area of the sample to be determinedusing the area occupied by a single layer of adsorbed gas molecule.Table 4 is a comparison of the active surface area of the ferric citrateof the present invention compared to the active surface area ofcommercially available ferric citrate compounds.

TABLE 2 BET active surface areas of various forms of ferric citrate MeanBET Dissolution Active Rates Surface Sample (mg/cm2/min) Area RFS-12-1(sigma/commercially 0.76 0.61 available) RFS-12-2 (sigma/commerciallyavailable) STM-134-1 (reference material 1) 2.47 16.17 STM-134-2(reference material 2) STM-182-1 (lab-scale 500 g 2.61 19.85 batch 1)STM-182-2 (lab-scale 500 g batch 2)

Example 3 Use of Ferric Organic Compounds According to the Invention inthe Treatment of Disorders

The ferric organic compounds produced according to the methods describedabove are useful in the treatment of hyperphosphatemia, metabolicacidosis, and any other disorders responsive to ferric organic compoundtherapy. Because the ferric organic compounds of the present inventionare more soluble than commercially available ferric organic compounds,smaller amounts of the ferric organic compounds of the present inventioncan be used to effectively treat patients suffering from such disorders.

Improved aqueous solubility is particularly relevant to the use of theferric organic compounds of the present invention in the treatment ofdisorders responsive to ferric organic compound therapy. Because theferric organic compounds of the present invention are more soluble, theywill be more effective when taken orally, and therefore can be taken inlower doses. The ferric organic compounds of the present invention aremore soluble over a wider pH range than commercially available ferricorganic compounds; therefore, the ferric organic compounds of thepresent invention can be more effective by being soluble in the smallintestine.

For example, in an experiment simulating the alkaline condition in thesmall intestine, the ferric citrate of the present invention showedbetter dissolution rate than the commercially available ferric citrate.It is suggested that the ferric citrate of the present invention can bemore effective by being more soluble in the small intestine. SeeTable 1. As a result, patients can take lower doses of medication withlower incidences of side effects.

In one embodiment of the invention, the ferric citrate of the presentinvention has a significantly higher rate of aqueous solubility underphysiological conditions than commercially available forms of ferriccitrate, and therefore the ferric citrate of the present invention isbelieved to provide a significant improvement in the orally effectiveuse of ferric citrate at a reduced dosage. By reducing the orallyeffective dose of ferric citrate, it is believed that the ferric citrateof the present invention will provide a lower incidence of ulcerativegastrointestinal adverse effects associated with commercially availableferric citrate compounds. In addition, it is believed that the increasedrate of dissolution of the ferric citrate of the present invention willprovide a more rapid onset of action in binding to dietary phosphate.

The ferric organic compounds of the present invention can beadministered in a number of forms, including orally administrable forms,which can comprise the ferric organic compounds of the present inventionalone or in combination with a pharmaceutically acceptable carrier. Theorally administrable form includes, but is not limited to, a tablet, apowder, a suspension, an emulsion, a capsule, a granule, a troche, apill, a liquid, a spirit, or a syrup. The composition can beadministered to human beings or other animals suffering from illnessesresponsive to ferric organic compound therapy.

Example 4 A Method of Making a Pharmaceutical-Grade Ferric Citrate

The present invention describes a process for manufacturingpharmaceutical-grade ferric citrate suitable as an active pharmaceuticalingredient for human use. An overview of the Ferric Citrate ManufactureFlow Chart is shown in FIG. 1. For a specific example,pharmaceutical-grade ferric citrate was produced using the proceduredescribed below. Also see FIG. 2.

4.1. Preparation of Ferric Chloride Solution

-   -   Weigh 550 g of ferric chloride hexahydrate (correct for CoA        purity) into a 1 L beaker.    -   Transfer the ferric chloride hexahydrate into a 4 L Erlenmeyer        flask.    -   Measure 1.1 L of deionized water using a graduated cylinder. Use        a small portion of the deionized water to rinse the beaker and        transfer the water into the 4 L Erlenmeyer flask. Transfer the        remaining water into the Erlenmeyer flask.    -   Stir solution using a magnetic stirring bar until completely        dissolved. The solution is a dark yellow to dark brown color.        4.2. Preparation of Sodium Hydroxide Solution    -   Weigh 244 g of sodium hydroxide (correct for CoA purity) into a        500 mL beaker.    -   Transfer the sodium hydroxide into a 2 L Erlenmeyer flask.    -   Measure 1.1 L of deionized water using a graduated cylinder. Use        a small portion of the deionized water to rinse the beaker and        transfer the water into a 4 L Erlenmeyer flask. Transfer the        remaining water into the Erlenmeyer flask slowly.    -   In a fumehood, stir the solution using a stirring bar while        adding the water and stir until completely dissolved. The        solution is clear and colorless.    -   Cool solution to below 30° C. using a water bath.        4.3. Preparation of Ferric Hydroxide Intermediate    -   Place a magnetic stirring bar into the ferric chloride solution        and place the flask in a water bath. Set up on a stirring plate        and start the stirring plate at a low speed.    -   Add slowly the sodium hydroxide solution to the ferric chloride        solution (at a rate of less than 20 mL/min) using an addition        funnel and control the temperature of the reaction mixture below        40° C. using the water bath and the rate of addition of sodium        hydroxide.    -   Continue to cool the brown viscous mixture to below 30° C. using        the water bath.    -   The final pH should be above 7. Use a suitable volume of 5 M        aqueous sodium hydroxide solution to correct the pH if not        above 7. Measure and record the final pH. A dark brown        precipitate of ferric hydroxide is formed.    -   If required, cool the brown viscous mixture to below 30° C.        using the cold water bath and filter the ferric hydroxide        suspension through 1 mm size stainless steel filter to break up        large precipitates.    -   Transfer equal amounts of ferric hydroxide suspension into four        500 mL centrifuge containers. Balance the weight of each        centrifuge container using a top-loading balance before        centrifugation.    -   Centrifuge the ferric hydroxide suspension at 1500 rpm and        25±5° C. for 5 minutes. Discard the supernatant.    -   Measure 2.5 L of deionized water using a graduated cylinder and        use approximately 1 L of water to re-suspend the ferric        hydroxide precipitate from the centrifuge containers.    -   Transfer the ferric hydroxide suspension into a 4 L Erlenmeyer        flask fitted with a 1 mm size stainless steel filter over a        glass funnel. Use the remaining 1.5 L of deionized water to        rinse the containers and wash the precipitate retained on the        stainless steel filter.    -   Wash the precipitate two more times by repeating the steps        beginning with “Transfer equal amounts . . . ”    -   After the third wash, recover the precipitate by repeating the        steps beginning with “Transfer equal amounts . . . ” and ending        with “Centrifuge the ferric hydroxide suspension . . . ”    -   Re-suspend the precipitate in 150 mL of deionized water.        4.4. Preparation of Ferric Citrate    -   Homogenize the ferric hydroxide precipitate using a mechanical        stirrer for 5 min in a 2 L Erlenmeyer flask.    -   Weigh 490 g of citric acid (correct for CoA purity) into a 500        mL beaker.    -   Place a stir bar in the 2 L Erlenmeyer flask in an oil bath and        stir at high speed.    -   Add the citric acid into the ferric hydroxide suspension.    -   Stir the solution for 30 minutes.    -   Heat the mixture at 90 to 100° C. (in oil bath) until the color        changes from orange-brown to a clear black-brown (for 30 to 120        min) or until ferric hydroxide precipitate is dissolved.    -   Take 1 mL aliquot of the reaction mixture in a 6 mL glass test        tube and centrifuge at 1500 rpm and 25±5° C. for 5 minutes.        Proceed to the next step if no precipitate is observed. If some        precipitate is observed add 10 to 34 g citric acid to the        mixture and continue heating for 10 to 30 min.    -   Terminate the heating and cool the mixture to below 30° C.        Measure the pH of the reaction mixture; it should be pH 0.8 to        1.5.    -   Transfer equal amounts of the reaction mixture into four 500 mL        centrifuge containers and balance the weight of each container        using a top-loading balance.    -   Centrifuge the reaction mixture at 1500 rpm and 25±5° C. for 5        minutes. Transfer and pool all the ferric citrate supernatant to        a clean 4 L Erlenmeyer flask.    -   Repeat the above 2 steps for all of the ferric citrate reaction        mixture.    -   Place one-half of the ferric citrate supernatant in a 4 L        Erlenmeyer flask and stir with a magnetic stir bar at high        speed.    -   Add slowly (over 20 min) 3.5 L of acetone (accurate volume        acetone calculated as five fold the supernatant volume) and stir        for an additional 10 min. A light-beige color precipitate forms.    -   Transfer the suspension into four 500 mL centrifuge containers        and balance the weight of each container using a top-loading        balance.    -   Centrifuge the ferric citrate suspension at 1500 rpm and        25±5° C. for 5 minutes.    -   Transfer and pool all the ferric citrate precipitate to a clean        4 L Erlenmeyer flask.    -   Repeat the above 4 steps with the second half of the ferric        citrate supernatant.    -   Pool all ferric citrate precipitate, add 1.4 L of acetone and        stir for 5 min.    -   Transfer the suspension into four 500 mL centrifuge containers        and balance the weight of each container using a top-loading        balance.    -   Centrifuge the suspension at 1500 rpm and 25±5° C. for 5        minutes.    -   Repeat the above 2 steps until all suspension is centrifuged.    -   Transfer and pool all the ferric citrate precipitate to a clean        4 L Erlenmeyer flask.    -   Repeat the above 5 steps two additional times (total of 3        washes).    -   Label and weigh drying trays, and record their weight.    -   Transfer the ferric citrate precipitate onto the drying dishes        and dry at ambient temperature (25±5° C.) for 16 hours.    -   Place the drying trays with precipitate into a vacuum oven and        dry at ambient temperature (25±5° C.) and under vacuum (about 20        mm Hg) for 8 to 16 hours (until the material appears ready for        grinding).    -   Reduce the particle size of the ferric citrate in a porcelain        mortar and pestle.    -   Place the ferric citrate powder into a vacuum oven and dry at        ambient temperature (25±5° C.) and under vacuum (about 20 mm Hg)        for 8 to 24 hours, until the material appears ready for sieving.    -   Finely reduce the ferric citrate particle size in a porcelain        mortar and pestle. Screen the ferric citrate powder through a 45        mesh size (355 micron) sieve.    -   Transfer the ferric citrate powder into drying trays and place        the trays in an oven to dry at 25±5° C. and under high vacuum        until the material appears dry (20 to 48 hours).    -   Transfer the powder into pre-weighed plastic amber containers.    -   Label and store the containers at ambient temperature and        protected from light.

Example 5 Method for Scalable Manufacture of Pharmaceutical-Grade FerricCitrate

The present invention provides a scalable manufacturing ofpharmaceutical-grade ferric citrate. Preferably, the ferric citratemanufacturing process is capable of producing at least 125 kg batches ofpharmaceutical-grade ferric citrate. An overview of the ferric citratemanufacturing is shown in FIG. 3. Details of the synthesis of ferriccitrate are shown in FIG. 4.

The scalable manufacturing process further employs fluidized bed dryerfor drying wet ferric citrate and for attaining release specificationsfor organic volatile impurities. See Table A for the Manufacture ReleaseSpecifications for Pharmaceutical-Grade Ferric Citrate.

Example 6 A Pharmaceutical-Grade Ferric Citrate

This invention provides a pharmaceutical-grade ferric citrate whichcomplies with the Manufacture Release Specifications as shown below inTable A. The pharmaceutical-grade ferric citrate of consistent purityand quality can be prepared using the manufacturing process of thepresent invention. See FIGS. 1-4 for the schematic diagram of the ferriccitrate manufacturing and quality control process. The ferric citratemanufacturing and quality control process can be readily scaled toproduce multi-kilogram batch sizes or scaled up to a manufacturingscale.

TABLE A Manufacture Release Specification for Pharmaceutical-GradeFerric Citrate Test Item Method Limit of Specification Appearance VisualLight brown to beige powder Purity of solid state ferric Calculate basedon LC/MS - flow NLT 90% w/w citrate injection quantitation and profile,anhydrous basis based on USP 25 <621>, <731>, <1086>, <736> Assaycontent of ferric LC/MS - flow injection profile, Run and report as %citrate non-related based on USP 25 <621>, <731>, w/w anhydrous basissubstances in solution state <1086>, <736> (attach table summary) Assaycontent purity of LC/MS - flow injection NLT 70% w/w ferric citrate andwater quantitation, based on USP 25 anhydrous basis adduct in solutionstate <621>, <731>, <1086>, <736> Assay content of citric acid LC/MS -flow injection NLT 10% w/w related substance in quantitation, based onUSP 25 anhydrous basis solution state <621>, <731>, <1086>, <736> Assaycontent of other LC/MS - flow injection profile, Run and report as %ferric citrate related based on USP 25 <621>, <731>, w/w anhydrous basissubstances in solution state <1086>, <736> (attach table summary)(excluding citric acid) Assay content of ferric iron Based on USP 25ferric sulfate NLT 16% w/w fresh assay weight basis Limit of ferrousiron Gravimetric method using NMT 1% w/w fresh potassium ferricynide,based on weight basis USP 25 <191> Loss on drying USP 25 <731> NMT 20%Hydrate (water content) Karl Fischer Titration NMT 20% USP 25 <921>water determination, Method Ia (Direct Titration) Identification MethodA: based on USP 25 Dark blue precipitate <191> ferric salt withK4Fe(CN)6 TS; reddish brown ppt with excess 1N NaOH; deep red color notdestroyed by mineral acids with NH4SCN TS Sample solution gives lightred color with pyridine and acetic anhydride Limit of chloride Based onUSP 25 Ferric sulfate NMT 5% procedures Reside on ignition Modified USP25 <281> Run and report Organic Volatile Based on USP 25 <467> Acetonenot more than Impurities 1000 ppm Limit of acid insoluble Gravimetricdetermination, based Not more than 0.02% substances on USP 25, ferricsulfate w/w fresh weight basis Trace/heavy metals USP 25 method <231> orAs < 0.3 ppm equivalent Others: run and report ICP for Zn, Cu, Sr, Ca,Na GFAAS for As Lead, Cadmium ICP-MS Pb < 5 ppm Cd < 2 ppm Mercury Coldvapor/AA Hg < 0.3 ppm Total iron content ICP NLT 16% w/w fresh weightbasis Microbial/Mold and USP Method <61> Yeast Salmonella Salmonella =negative E. Coli E. Coli = negative Coliforms Total Coliforms <3 cfu/gTotal aerobic count Total aerobic count <10 cfu/g Total combined moldand yeast Total mold and yeast <20 cfu/g

Example 7 Raw Material Release Testing Specifications

TABLE B Ferric chloride hexahydrate Release Specifications Test ItemMethod Limit of Specification Appearance Visual Yellow to yellowishbrown powder, crystals or chunks Identification - USP 25 <191> Yielddark blue precipitate with Ferric salts potassium ferrocyanide TS Formreddish brown precipitate with excess 1N NaOH Red deep color withammonium thiocyanate TS and color not destroyed by dilute mineral acidsIdentification - USP 25 <191> Aqueous solution of ferric chlorideChloride yields with 0.1N silver nitrate TS a white, cruddy precipitate,which is insoluble in nitric acid but is soluble in a slight excess of6N ammonium hydroxide Heavy metals ICP-MS As < 0.1 ppm Cd < 0.1 ppm Hg <0.1 ppm Pb < 0.1 ppm Assay - Ferric USP 25, Assay >18% iron ferricsulfate, p. 2303

TABLE C Sodium Hydroxide Release Specifications Test Item Method Limitof Specification Appearance Visual White pellets, odorlessIdentification - USP25, <191> No precipitate is formed with Sodiumpotassium carbonate A dense precipitate is formed with potassiumpyroantimonate An intense yellow color to a non- luminous flame

TABLE D Deionized Water Release Specification Test Item Method Limit ofSpecification Appearance Visual Clear, colorless and odorless Mineralscan ICP-MS As < 0.001 ml/L Cd < 0.0002 ml/L Pb < 0.001 ml/L Hg < 0.02μg/L Total Organic Standard <1 mg/L Carbon Method for the Examination ofWater and Wastewater, 20^(th) ed. Total Hardness Standard <4 mg/L Methodfor the Examination of Water and Wastewater, 20^(th) ed. Total Plate USP25 method <10 cfu Count <61> Total Coliform USP 25 method <3 cfu Count<61>

TABLE E Acetone Release Specification Test Item Method Limit ofSpecification Appearance Visual Clear colorless liquid Identification -USP 25, The IR absorption of a thin film Acetone p.2502, FTIR betweenKBr plates exhibits a strong band at about 5.8 μm; a strong region ofabsorption between 6.8 and 7.5 μm, with maxima at about 7.0 and 7.3 μm;a strong maximum at about 8.2 μm; and a weak maxima at about 9.2 and11.0 μm. Assay From NLT 99.5% manufacturer's Certificate of Analysis(result from GC method preferred) Aldehyde From NMT 0.002% (as HCHO)manufacturer's Certificate of Analysis Isopropyl From NMT 0.05% alcoholmanufacturer's Certificate of Analysis Methanol From NMT 0.05%manufacturer's Certificate of Analysis Residue after From NMT 5 ppmevaporation manufacturer's Certificate of Analysis Acids From NMT 0.0003meq manufacturer's Certificate of Analysis (result from titrimetrictest) Bases From NMT 0.0006 meq manufacturer's Certificate of Analysis(result from titrimetric test) Water From NMT 2% manufacturer'sCertificate of Analysis Insoluble From filtered through ≦0.45 μm filtersubstances manufacturer's Certificate of Analysis or filtered through≦0.45 μm filter

TABLE F Citric Acid Release Specification Test Item Method Limit ofSpecification Appearance Visual White or colorless crystals or powderIdentification - USP 25 <191> A light red color is Citrate produced

Example 8 Final Product Manufacture Release Testing Methods

The following tests are performed to ensure the final ferric citrateproduct prepared according to the method or process of the presentinvention complies with the established Manufacture ReleaseSpecification as shown in Table A. The Manufacture Release Specificationmay be readily modified or revised by one of ordinary skill in the artfollowing the teaching of this invention to enhance the purity andsafety of the pharmaceutical-grade ferric citrate for human use.

-   -   (a) Based on USP 25 <191> Gravimetric method using potassium        ferricyanide, p. 1918—Limit of Ferrous Iron in Ferric Citrate    -   (b) Based on USP 25, ferric sulfate assay, p. 728—Limit of        Chloride in Ferric Citrate    -   (c) Based on USP 25, ferric sulfate assay, p. 728—Limit of Acid        Insoluble Substances in Ferric Citrate    -   (d) Based on USP 25, ferric sulfate assay, p. 728—Assay Content        of Ferric Iron in Ferric Citrate    -   (e) Based on USP 25 <467>—Determination of Acetone in Ferric        Citrate Samples by GClFID Headspace    -   (f) Based on USP 25 <191> Ferric Salts; Citrate, p.        1918—Identification of Ferric Citrate    -   (g) Based on USP 25 <621>, p. 1988-1995, <731>, <1086>, p.        2157-2159, <736>, p. 2029-2033—LCMS Flow-Injection Quantitation        and Profile of Ferric Citrate and Related Substances    -   (h) USP 25 <731> Loss on Drying    -   (i) USP 25 <921> Water Determination, Method Ia (Direct        Titration)    -   (j) ICP for Zn, Cu, Sr, Ca, Na and total iron    -   (k) GFAAS for As    -   (l) ICP-MS for lead and cadmium    -   (m) Cold vapor/AA for mercury    -   (n) Residue on ignition    -   (o) Microbial/mold and yeast

Example 9 Methods of Using and Testing the Pharmaceutical-Grade FerricCitrate in Patients In Vivo

A. Handling and Forms of Test Compositions

Ferric citrate is supplied in 500 mg capsules, whereas the placebo willbe provided in identical-looking capsules (indistinguishable from thosecontaining the active drug); the placebo capsules will contain sorbitoland colorant to match the powder color of the active capsules. Theplacebo capsule shells will be identical to the active capsule shells.

Storage

All study drug supplies must be stored under secure conditions and arenot to be used after their expiration date, which is imprinted on thestudy drug container. The study drugs should be kept under controlledconditions (15 to 30° C.; 59 to 86° F.) in a tightly closed container,protected from light.

Dosage

A recent pilot study compared ferric citrate (3 g daily) to calciumcarbonate (3 g daily) for reducing serum P0₄ in patients with End StageRenal Disease (ESRD). Although ferric citrate caused a significantdecrease in serum P04, it was not as effective as calcium carbonate.This dose of ferric citrate was associated with mild, but tolerable GIsymptoms.

As shown in FIGS. 12 and 13, treatments using pharmaceutical-gradeferric citrate provide several advantages over chemical grade ferriccitrate. In general, while pharmaceutical-grade ferric citratedemonstrates an efficacy approximately equal to that of chemical gradeferric citrate, it achieves this result with less adverse side effectsthan chemical grade ferric citrate.

FIG. 12 also indicates that adverse side effects associated withadministering pharmaceutical-grade ferric citrate were not statisticallydifferent from those associated with the placebo. An advantage of thissafety profile is that an individual patient may have his dosing ofpharmaceutical-grade ferric citrate titrated over a broad range of doseswith less concern about side effect. In this way, a patient's individualtreatment may be tailored to suit his specific needs and tolerances.

The doses of ferric citrate chosen for study or treatment may be from 1to 30 grams of ferric citrate per day. In part, this may depend on thenature of the formulation provided. For example, ferric citrate capsulesmay be administered up to a daily dose of about 15 grams/day, whereasthe tablet form may be administered up to 30 grams/day. Thus, there is avery broad range of dosing regimens encompassed by the invention.

Titration of Optimal Dosage for a Subject

In the context of this invention, the term “subject” refers to either ahuman or non-human animal.

The optimal dosage of an individual subject or groups may be determinedas follows. A dose of approximately one or two grams per day is merelysuggested as an illustrative starting dose. The daily dose may beincreased as needed until the desired result is observed.

The intent of the invention is to not limit the dose range employed.Therefore, depending on the subject(s) the daily dose administered mayapproximate thirty, forty, fifty, sixty, seventy, eighty, ninety or onehundred grams per day. The safety profile of the pharmaceutical-gradeferric citrate allows the implementation of a broad range of doses.

Further, it is the intent of the invention to not be limited to capsulesand tablets as oral formulations. It is known in the art that a widevariety of oral formulations may be adapted for use with the invention.

Illustrative Example of a Dosage Regimen

An non-limiting example of a dosing regimen is provided below. This isnot meant to limit the invention as to how an effective amount of ferriccitrate is selected, or the form in which it is provided or thefrequency of administering the composition per day. The following merelyillustrates how ferric citrate and placebo may be administered; e.g., as500 mg capsules of identical appearance. All patients may receive (in ablinded fashion) 4 capsules with each of three meals, on a daily basis,for days. Patients will be instructed to take the study medicationwithin 10 minutes of finishing their meals (breakfast, lunch, anddinner).

The number of placebo, and active capsules to be taken at each meal, areas follows:

Placebo arm of the study

-   4 placebo capsules, with breakfast-   4 placebo capsules, with lunch-   4 placebo capsules with dinner    Ferric citrate 2 g per day arm of the study-   1 ferric citrate capsule and 3 placebo capsules with breakfast-   1 ferric citrate capsule and 3 placebo capsules with lunch-   2 ferric citrate capsules and 2 placebo capsules with dinner    Ferric citrate 4 g per day arm-   2 ferric citrate capsules and 2 placebo capsules with breakfast-   3 ferric citrate capsule and 1 placebo capsule with lunch-   3 ferric citrate capsules and 1 placebo capsule with dinner    Ferric citrate 6 g per day arm-   4 ferric citrate capsules with breakfast-   4 ferric citrate capsules with lunch-   4 ferric citrate capsules with dinner    B. Clinical Schedule and Assessments    Duration of Study Treatment

Each patient's participation in the trial lasts for up to 8 weeks: thescreening period (approximately 1-2 weeks), a 1-2 week washout, and 4weeks of treatment with study medication.

Screening Visit 1 (Study Days −30 to −15)

The following procedures will be performed at the first screening visit:

-   1. Medical history, including concomitant medications.-   2. Demographic data.-   3. Physical examination, including height, weight, and vital signs.-   4. Dietary interview, using 24 hour recall method, to assess dietary    intake of calcium and phosphorous, three times during screening    period, to include one dialysis day, one non-dialysis day, and one    weekend day. Note: Dietary interview may be also performed, in part    or in whole, during the washout period.-   5. Laboratory assessment:    -   Hematology: complete blood count (CBC) with differential,        platelets.    -   Chemistries: sodium, potassium, chloride, bicarbonate, blood        urea nitrogen (BUN), creatinine, glucose (random), aspartate        transaminase (AST), alanine transaminase (ALT), alkaline        phosphatase (ALP), total bilirubin, total protein, albumin,        serum calcium, serum phosphate, magnesium    -   Total and LDL cholesterol levels    -   Serum (3-HCG for women of childbearing potential    -   Iron panel: serum iron, ferritin, transferrin saturation        percentage, and total iron binding capacity.        6. 12-lead ECG.        7. Patients will be given instructions for the Washout Period        (Study Days −14 to −1):-   a. All phosphate-binding agents will be discontinued at Day −14-   b. Any iron therapy (oral or intravenous) will be discontinued at    Day −14-   c. Patients who have been receiving a stable dose of vitamin D or    calcitriol for I month prior to enrollment will be instructed to    maintain their current dose throughout the study-   d. Patients will be advised to avoid changes in diet, calcium or    magnesium containing antacids (other medications).    Screening Visit 2 (Study Days −7+/−1 Day)    1. Laboratory Assessment:-   Serum P0₄-   Note: Patients with a Day −7 serum P0₄ ≧5.5 mg/dL and ≦10 mg/dL may    be randomized before the 2-week washout is complete. The day of    randomization will automatically become Day 0.-   Note: Patients with a Day −7 phosphate level of ≧10 mg/dL will be    removed from the study and instructed to resume their pre-study    medications.    Study Day 0 (Randomization and Dosing)-   1. Physical examination, including weight and vital signs.-   2. Adverse event query.-   3. Concomitant medication query.-   4. Baseline Laboratory assessments:    -   Serum P04    -   Serum Ca    -   Iron panel: serum iron, ferritin, transferrin saturation        percentage, and total iron binding capacity

Note: The Baseline Laboratory Assessments may be done up to 3 days priorto Day 0

-   5. Patients with a P0₄ level ≧0.5 mg/dL and ≦10 mg/dL will be    randomized and a 15-day supply of study medication will be    dispensed.

Note: Patients should be instructed to begin taking study medicationwithin 10 minutes of completing their next meal on Day 0.

Study Day 14 (Midpoint Evaluation)

The following procedures will be performed at Study Day 14+/−1 day.

-   1. Physical examination including weight and vital signs.-   2. Adverse event query.-   3. Concomitant medication query.-   4. Dispense an additional 15-day supply of study medication.

All returned capsules should be counted and recorded in the Case ReportForm.

-   5. Laboratory assessment:    -   Hematology: CBC with differential, platelets.    -   Chemistries: sodium, potassium, chloride, bicarbonate, BUN,        creatinine, glucose (random), AST, ALT, ALP, total bilirubin,        total protein, albumin, calcium, phosphate, magnesium.    -   Iron panel: serum iron, ferritin, transferrin saturation        percentage, and total iron binding capacity.    -   Total and LDL cholesterol levels.

Note: Patients with a Day 14 phosphate level of >10 mg/dL will beremoved from the study and instructed to resume their pre-studymedications.

Study Day 28 (End of Study Evaluation)

The following procedures will be performed at Study Day 28+/−1 day or onthe day of early termination.

-   1. Physical examination including weight and vital signs-   2. Adverse event query.-   3. Concomitant medication query.-   4. Laboratory assessment:    -   a. Hematology: CBC with differential, platelets    -   b. Chemistries: sodium, potassium, chloride, bicarbonate, BUN,        creatinine, glucose (random), AST, ALT, ALP, total bilirubin,        total protein, albumin, calcium, phosphate, magnesium.    -   c. Total and LDL cholesterol levels        -   d. Iron panel: serum iron, ferritin, transferrin saturation            percentage, and total iron binding capacity.-   5. 12-lead ECG-   6. Patients will be instructed to resume their pre-study medications    after completing the study.    C. Data Management and Analysis

GloboMax will be the primary data management, monitoring, andcoordinating center. Case report forms (CRF) will be provided for eachsubject. Subjects will not be identified by name or initials on CRFs.The CRF will be monitored at the clinical sites and collected byGloboMax's study monitor. Audited CRFs will be used to create electronicdata files.

Three major categories of endpoints reflect biochemical and clinicalissues being addressed at the outset. Additional clinical andbiochemical issues are addressed as they arise. Therefore, the endpointsare not meant to limit the totality of relevant findings andmeasurements collected in these, or future studies.

Primary Endpoints (see FIGS. 9-10)

-   -   The change in serum P0₄ concentration at Days 14 and 28 from        baseline.        Secondary Endpoints (see FIGS. 9-10)    -   The change in serum calcium concentration at Days 14 and 28 from        baseline.    -   The change in iron, ferritin, transferrin saturation percentage,        and total iron binding capacity at Days 14 and 28 from baseline.    -   The change in the Ca′PO₄ product at Days 14 and 28 from        baseline.

It is further noted that in comparison to chemical grade ferric citrate,the pharmaceutical grade ferric citrate demonstrates similar efficacy.See FIG. 13. However, the safety profiles indicate that thepharmaceutical grade generally results in less adverse clinical effects.See FIG. 13.

Safety Endpoints (see FIG. 11)

-   -   Safety will be monitored by recording adverse events (FIG. 11)        and the results of physical examinations, vital signs and        laboratory tests at each study visit.    -   Specific rules for withdrawal from the study, based on        laboratory data, have also been set up to ensure patient safety.        A nonlimiting example of such criteria is illustrated by the        following:        -   If a patient's serum phosphate level increases to ≧10 mg/dL            at any time during the study period, the patient will be            withdrawn from the study.

Specific studies have also shown that pharmaceutical grade ferriccitrate possesses similar efficacy to chemical grade ferric citrate.(See FIG. 13). However, the pharmaceutical grade generally affords asignificantly more desirable safety profile as shown in FIG. 12. Thisindicates an important advance in regulating serum phosphate levels.

1. A pharmaceutical composition comprising ferric citrate having a BETactive surface area of at least 16 sq. m/g and a pharmaceuticallysuitable carrier, wherein the ferric citrate is present in an amounteffective to reduce serum phosphate levels.
 2. The pharmaceuticalcomposition of claim 1, wherein the ferric citrate has an intrinsicdissolution rate of 1.88-4.0 mg/cm²/min.
 3. The pharmaceuticalcomposition of claim 1, wherein the effective amount of ferric citrateis from 2 grams per day-30 grams per day.
 4. The pharmaceuticalcomposition of claim 1, wherein the effective amount of ferric citrateis from 4 grams per day-15 grams per day.
 5. The pharmaceuticalcomposition of claim 1, wherein the effective amount of ferric citrateis from 2 grams per day-12 grams per day.
 6. The pharmaceuticalcomposition of claim 1, wherein the effective amount of ferric citrateis selected from 2 grams per day, 4 grams per day and 6 grams per day.7. The pharmaceutical composition of claim 1, wherein the effectiveamount of ferric citrate is 1 gram per day.
 8. The pharmaceuticalcomposition of claim 1, wherein the effective amount of ferric citrateis 500 mg per unit dosage form.
 9. A pharmaceutical compositioncomprising 500 mg of ferric citrate having a BET active surface area ofat least 16 sq. m/g, and a pharmaceutically suitable carrier, whereinthe pharmaceutical composition is in a capsule dosage form.